The present invention relates to a machine for producing and dispensing liquid or semi-liquid consumer food products.
The invention in particular refers, although this does not represent a limitation, to machines for production and distribution of water-ices, sorbets, ice-creams, soft ice-creams, cream, chocolate, yogurts and the like and to machines for production and preservation of mixtures for ice-cream, chocolate, creams, sauces, soups and mixtures in general, and the like.
As known, these machines comprise a holding tank for a liquid base product, and a treatment circuit for the base product, for obtaining said consumer food product. The latter can be then dispensed by means of suitable delivery devices and/or kept in a preservation tank.
The treatment circuit may comprise, depending on the type of machine taken into consideration, thermal treatment means, to cool or heat the product, a whisking cylinder to keep the product to a given viscosity degree, mixing means to mix the base product with an auxiliary product, such as flavorings, etc.
Generally, the machines are provided with a plurality of actuators, interlocked with a control unit so that the different working steps according to a preset program are carried out on the base product.
Known machines are generally provided with a protection or shield enabling the operators to accede to the batch freezing chamber where an ice-cream for example is being batch frozen.
It may happen that the shield is opened while the machine is working, i.e. while a stirrer that is inside the batch freezing chamber is rotating about its axis. The machine can be provided with a control system that when the shield is opened during operation of the machine, carries out switching off of the motor dedicated to movement of the stirrer, so that the risks of the operator being injured are prevented (or at least reduced).
It should be however noted that, in spite of the presence of this safety system, due to the inertia of the mass associated with the rotating system, stopping of the stirrer in a reasonably quick time is impossible so that there is a non-negligible risk for the operator being injured.
A further drawback characteristic of the machines of known type resides in that an ice layer tends to be formed on the inner surface of the batch freezing chamber, due to the presence of the evaporator of the refrigerating circuit exactly in register with the outer surface of said chamber. Ice formation, in addition to impairing heat exchange, tends to hinder correct operation of the stirrer and therefore adversely affects the quality of the obtained food product.
Presently available are scraping elements for removal of the ice layer which are mounted on the stirrer's outer profile. These elements however are not able to efficiently work and do not allow full removal of the ice tending to be formed within the whisking implement.
Another disadvantage of the machines according to the known art comes out if it is considered that sometimes a homogeneous and compact ice-cream block is formed close to the stirrer's center which does not enable a correct texture to be obtained and therefore adversely affects both the organoleptic features of the product and the time required for terminating preparation of same; sometimes due this ice-cream block the batch freezing operation on the ice-cream cannot be completed, which will bring about a greater energy consumption by the actuator dedicated to actuation of said stirrer.
Removal of this ice-cream block is presently very complicated and time-consuming, as it is necessary to stop the process, bring the ice-cream mixture to the liquid state again and restart with a new batch freezing cycle.